Meaning Of a "CONSTRAINT"

What is a constraint actually ?
Why are Constraints Necessary?
And what are the different types of Constraints available in Oracle supported SQL?
Edited by: Tejaswi.B on Jan 11, 2011 12:39 AM

Constraints "constrain" the data values that you allow to be in your database.
Once defined/declared, the DBMS will enforce them.
From a database theory perspective, constraints can be classified as follows.
- Attribute (single column) constraints.
These are constraints that restrict single values in a column.
For instance: Gender must be Male or Female.
The SQL CHECK construct can be use to implement these kind of constraints.
- Tuple (single row / mutliple column) constraints.
These are constraints that restrict combinations of values in two or more columns (in a same row).
For instance: Presidents must earn a salary that's more than 8000.
The SQL CHECK construct can be use to implement these kind of constraints.
- Table (multi row) constraints.
These are constraints that restrict combinations of rows in a single table.
For instance: cannot have more than one president in the emp table.
The SQL ASSERTION construct can be used to implement these kind of constraints.
However: this construct is not supported/delivered by any DBMS vendor (Oracle included).
We do have special-case syntax for some subclasses of table constraints that frequently occur in database designs: most notably KEYS (primary/unique).
- Database (multi table) constraints.
These are constraints that restrict combinations of rows accross two or more tables.
For instance: The Sales department cannot employ Trainers.
The SQL ASSERTION construct can be used to implement these kind of constraints.
Yet is not available...
We do have special-case syntax for a frequently occuring subclass of database constraints: the foreign key.
From a database-centric point of view all constraints are ideally implemented inside the DBMS.
- Declaratively whenever possible.
- Procedurally otherwise. This involves generating triggers to enforce them.
(or using tricks with materialized views and/or function based indexes for special cases).

Similar Messages

DEFERRABLE Constraint State Meaning ??

Hello,
I checked the documentation about the meaning of DEFERRABLE constraint state here and in particular following section
DEFERRABLE Clause
The DEFERRABLE and NOT DEFERRABLE parameters indicate whether or not, in subsequent transactions, constraint checking can be deferred until the end of the transaction using the SET CONSTRAINT(S) statement. If you omit this clause, then the default is NOT DEFERRABLE.
Specify NOT DEFERRABLE to indicate that in subsequent transactions you cannot use the SET CONSTRAINT[S] clause to defer checking of this constraint until the transaction is committed. The checking of a NOT DEFERRABLE constraint can never be deferred to the end of the transaction.
If you declare a new constraint NOT DEFERRABLE, then it must be valid at the time the CREATE TABLE or ALTER TABLE statement is committed or the statement will fail.
Specify DEFERRABLE to indicate that in subsequent transactions you can use the SET CONSTRAINT[S] clause to defer checking of this constraint until after the transaction is committed. This setting in effect lets you disable the constraint temporarily while making changes to the database that might violate the constraint until all the changes are complete.What I understood from above was if the constraint is created as DEFERRABLE, then it is possible to change its status to DEFERRABLE(i.e. check the validity at the end of transaction) / IMMEDIATE(i.e. check the validity at the end of statement). However, my following test shows that just having constraint defined as DEFERRABLE is enough to postpone the constraint validation to the end of transaction. Is the documentation incorrect or am I missing something obvious here?
SQL> select * from v$version ;
BANNER
Oracle Database 10g Release 10.2.0.5.0 - Production
PL/SQL Release 10.2.0.5.0 - Production
CORE    10.2.0.5.0      Production
TNS for Linux: Version 10.2.0.5.0 - Production
NLSRTL Version 10.2.0.5.0 - Production
SQL> DROP SEQUENCE P_SEQ ;
Sequence dropped.
SQL> DROP TABLE C PURGE ;
DROP TABLE C PURGE
ERROR at line 1:
ORA-00942: table or view does not exist
SQL> DROP TABLE P CASCADE CONSTRAINTS PURGE ;
Table dropped.
SQL> CREATE TABLE P (PID NUMBER, CONSTRAINT P_PK PRIMARY KEY (PID)) ;
Table created.
SQL> CREATE SEQUENCE P_SEQ minvalue 1 start with 1 increment by 1 cache 10 ;
Sequence created.
SQL> CREATE TABLE C (CID NUMBER, PID NUMBER, CONSTRAINT C_PK PRIMARY KEY (CID), constraint c_fk foreign key (pid) references P(PID) deferrable initially immediate) ;
Table created.
SQL> select CONSTRAINT_NAME, TABLE_NAME, R_CONSTRAINT_NAME, status, DEFERRABLE, DEFERRED from USER_CONSTRAINTS ;
CONSTRAINT_NAME                TABLE_NAME                     R_CONSTRAINT_NAME              STATUS   DEFERRABLE     DEFERRED
C_FK                           C                              P_PK                           ENABLED DEFERRABLE     IMMEDIATE
P_PK                           P                                                             ENABLED NOT DEFERRABLE IMMEDIATE
C_PK                           C                                                             ENABLED NOT DEFERRABLE IMMEDIATE
SQL> CREATE OR REPLACE TRIGGER C_BI_TRG
2 BEFORE INSERT ON C
3 FOR EACH ROW
4 BEGIN
5    IF :NEW.PID IS NULL THEN
6      INSERT INTO P VALUES (P_SEQ.NEXTVAL) RETURNING PID INTO :NEW.PID ;
7    END IF;
8 END;
9 /
Trigger created.
SQL> SELECT * FROM P ;
no rows selected
SQL> SELECT * FROM C ;
no rows selected
SQL> INSERT INTO C VALUES (1, NULL) ;
1 row created.
SQL> SELECT * FROM P ;
       PID
      1
SQL> SELECT * FROM C ;
       CID       PID
      1         1
SQL> commit ;
Commit complete.

You are right, I overlooked that. Example about the difference:
SQL> create table t (n number);
Table created.
SQL> alter table t add constraint c primary key (n) deferrable initially immediate;
Table altered.
SQL> insert into t values (42);
1 row created.
SQL> commit;
Commit complete.
SQL> insert into t values (42);
insert into t values (42)
ERROR at line 1:
ORA-00001: unique constraint (SCOTT.C) violated
SQL> alter session set constraints=deferred;
Session altered.
SQL> insert into t values (42);
1 row created.
SQL> commit;
commit
ERROR at line 1:
ORA-02091: transaction rolled back
ORA-00001: unique constraint (SCOTT.C) violatedKind regards
Uwe Hesse
http://uhesse.wordpress.com

Use multiple primary keys to create DB constraint

Hi,
Is it possible to have multiple primary keys within one EJB to create a DB including the constraints, if so how? Is there an example of this or any example which uses multiple primary keys to create a DB?
Thanks,
Maarten

"Is it possible to have multiple primary keys within one EJB..."
If you mean a composite key, yes. Your PrimaryKeyObject would have one attribute for each column that makes up your composite key. If that's not what you meant, please clarify.
"...to create a DB including the constraints"
Not sure what you mean here. Constraints are enforced by the DB, and you don't create databases with EntityBeans.

CFIMAGE not working with certain JPG

Hi all,
Got an emergency here, hope anyone can help.
I find that more and more people are encountering problems using CFIMAGE -- no error is thrown when reading/saving certain jpg images, but the result image is just blank and gray.
The code is just simple:
<CFSET IM=ImageRead("C:\DSCN1570.JPG")>
<cfset ImageResize(IM,300,200,"highPerformance")>
<cfset ImageWrite(IM,"C:\DSCN1570-2.JPG")>
or even just:
<CFSET IM=ImageRead("C:\DSCN1570.JPG")>
<cfset ImageWrite(IM,"C:\DSCN1570-2.JPG")>
This happens after applying the latest hotfix for 8.0.1 (Cumulative Hotfix 2 for CF 8.0.1). If this patch is not installed the processing works.
Attached is an offending file. The code works if i replace the file with another jpg.
Any help is much appreciated. I'm running CF 8,0,1,195765 devt edition on Windows XP and my java version is 1.6.0_04. My metadata-extractor is 2.3.1.
Thanks,
Andrew

Yeah, sorry: missed the bit - that BKBK pointed out - about you saying you did some testing. To be honest, I would never release code into production without load-testing it first. Especially something that's perhaps already red-flagged as being a risk. Of course there was no real reason for you to think that the previously fixed issue had been regressed. So not - perhaps - a red flag. maybe just an amber one.
I don't believe load testing is a "nice to have", it's essential. In the past I just slapped my code into production after a bit of a click round to make sure it all seemed to work. Then we released some code which worked fine whilst only one person was accessing it, but had some severe logic flaws in it which made it fail - in a data-destroying sort of way - which caused us an awful lot of issues with the client (which in turn got me shouted @ by the boss), not to mention wasted time fixing everything.
That lead me to investigate whether we could have found that sort of thing had we load-tested: yes. Easily. Lesson learned. It also turned up a few other things we didn't notice which were easy tweaks which improved the performance of the app, and made the client happy again.
But anyway, that's just something to think about for future reference, I guess. I fully understand what you mean about time constraints often preventing one from taking the perfect foolproof approach to things: we've all done that. Just sux you got caught out by it.
As for bringing it to Adobe's attention... go here: http://cfbugs.adobe.com/cfbugreport/flexbugui/cfbugtracker/main.html.
It'd help if you could contrive a stand-alone test rig that can be made to fail under load.
Adam

System Copy on Microsoft Cluster

Hi,
We have ECC 6.0 SR2 with Microsoft Cluster on Oracle 10.2 & Windows
2003 Enterprise edition 64bit.
Installation is ABAP+java stack
Installation of CI and DB on same host.
Virtual hostname for database is ORACLEOT1
Virtual hostname for CI is SAPOT1
We have taken Database Instance Export using sapinst sapint_use_hostname=ORACLEOT1
command and executed from command prompt, Export completed successfully.
Now, we are trying to export the Central Instance using the same command and encountered error will Export ABAP
The step runR3szchk it is showing Error
Error log:
ERROR: ExeModify for write_ddloadd failed in row 42876
       (rc = 26)
       objectname   = /1CN/LRMSCALEV02~0
       objecttype   = PRKEY APPL0
       tabart       = APPL0
       rowcount     = 0
error message returned by DbSl:
(null)
Please also suggest us for CI export, whether we need to give virtual
hostname of virtual hostname of Database or Virtual hostname of CI.
Regards,
$@ndy

Hello,
rc=26 means ' Primary key constraint violated '.Please check the
object    /1CN/LRMSCALEV02~0 according to the
note 130648 R3load export: Write_ddloadd failed (rc=101)
Also update the kernel and dbsl files from marketplace and try export again
note 19466
regards,
John Feely

Arbitrary ordering?

Querying dba_constraints, I might finish with an 'order by constraint_type'. But this now means that unique constraints are listed after foreign keys because 'R' sorts before 'U'. If I'm running the query to generate the SQL to re-create the constraints, I'll get a lot of failures because the foreign keys are supposed to reference primary or uniquely-constrained columns, and the unique constraints won't have been created yet. It's no good me ordering by constraint_type desc, either, because then I'll be trying to create foreign keys before the primary keys get created, because 'R' would sort before 'P'. What I really need is all the primary constraints, then all the uniques and all the foreign keys bringing up the rear.
So my question: is there a way of ordering by a column in an arbitrary, user-defined way? Where you say, for example, "order by constraint_type ('P','U','C','R')".
A bit like list partitioning, where you get to define what "constrains" a record to a partitcular partition, only this time, you get to define your ordering sequence.
As another example, I want to sort the EMP table in department number order, but the ordering I want is "20, then 10, then 40 and then 30", for whatever weird business reason you might think up.
Do-able in a simple (or not-so simple) query? I can see how four separate union queries could do it... am wondering if there's anything more elegant and that could extend easily to lots more than 4 distinct ordering values.

Decode the constraint type and order by the decoded column. In SQLPlus, you can even NOPRINT the ordering column.
SQL> create table hkc_test_90 (table_name varchar2(30), col_name varchar2(30), constraint_type varchar2(1));
Table created.
SQL> insert into hkc_test_90 values ('T_A','C_1','P');
1 row created.
SQL> insert into hkc_test_90 values ('T_A','C_3','U');
1 row created.
SQL> insert into hkc_test_90 values ('T_B','C_1','P');
1 row created.
SQL> insert into hkc_test_90 values ('T_B','C_2','R');
1 row created.
SQL> insert into hkc_test_90 values ('T_C','C_1','P');
1 row created.
SQL> insert into hkc_test_90 values ('T_C','C_4','R');
1 row created.
SQL> commit;
Commit complete.
SQL>
SQL> select table_name, col_name, constraint_type, decode(constraint_type,'P',1,'U',2,'C',3,'R',4) ctype_no
2 from hkc_test_90
3 order by ctype_no, table_name;
TABLE_NAME                     COL_NAME                       C   CTYPE_NO
T_A                            C_1                            P          1
T_B                            C_1                            P          1
T_C                            C_1                            P          1
T_A                            C_3                            U          2
T_B                            C_2                            R          4
T_C                            C_4                            R          4
6 rows selected.
SQL> col ctype_no noprint
SQL> select table_name, col_name, constraint_type, decode(constraint_type,'P',1,'U',2,'C',3,'R',4) ctype_no
2 from hkc_test_90
3 order by ctype_no, table_name;
TABLE_NAME                     COL_NAME                       C
T_A                            C_1                            P
T_B                            C_1                            P
T_C                            C_1                            P
T_A                            C_3                            U
T_B                            C_2                            R
T_C                            C_4                            R
6 rows selected.
SQL>
Hemant K Chitale

Validating only new data

Hi.
Is there possible, after disabling constraints, populating new data into tables and enabling constraints again, to validate only new data and not the old one?
(DB: 10gR2 and newer...)

Karthick_Arp wrote:
Your old data are already on constraints. So when you disable and add new data and then enable the constraint the old data will not give you any issue. If at all you have any issue it will be with the new data.May you tell me why you're so sure? I have already read the documentation from boopathi's post and there is nothing mentioned about that.
From http://download.oracle.com/docs/cd/B28359_01/server.111/b28318/data_int.htm#i4773 :
Constraint States
* ENABLE ensures that all incoming data conforms to the constraint
* DISABLE allows incoming data, regardless of whether it conforms to the constraint
* VALIDATE ensures that existing data conforms to the constraint
* NOVALIDATE means that some existing data may not conform to the constraint
In addition:
* ENABLE VALIDATE is the same as ENABLE. The constraint is checked and is guaranteed to hold for all rows.
I am now confused.
So you mean that when constraint is disabled the SCN of this operation is remembered and during ENABLE VALIDATE only rows with higher SCN are validated?

1 position, 1 person, 2 chiefs

Hi everyone,
I need to know, how to add the following issue into OM: 1 position (1 person) with 2 chiefs in 2 differents organizational unit.
Thanks,
Ruben

Hi Ruben,
If it deleted the first O-P relationship when you created the second one, means the time constraint for that relationship is set to "1" or "2" meaning you can have a position related only to one organizational unit at a time. This can be changed, but it will affect all positions, so that they may be assigned to more than one organiational unit.
In the IMG: Personnel Management --> Organizational Management --> Basic Settings --> Data Model Enhancement --> Maintain Relationships. Select the 003 relationship and then the folder "Time Constraints" on the left side. Go down the list to the object type "S" appears and the A003 "Belongs to" relationship. On the right, the entry is probably "2". Change this to "3" and Save. This will now allow you to have a position belong to more than one org unit.
Again, this will now apply to all positions, so if you do a reorganization, for example, you must make sure the old relationships are delimited manually as they will not be done automatically as they would be if the time constraint remained "2". So I ask - is this what you really want? Does this person really report to two different chiefs in two different organizations? Or is one a "dotted line" or functional oversight relationship. After the change, this individual will now appear in each manager's organization and either one would be able to approve time, grant pay increases, approve vacations, etc.
It can be done. Are you sure it is necessary to do this?
Paul

Calculating Remain Finish Date/ Remain Start Date

Problem:
I have an issue where I can't change the finish date because the following error message: Remain Finish date cannot be earlier than Remain Start Date.
I want to change end date to Jan 25 but it keeps calculating/inputting Feb. 18
Observed:
All the Predecessor for this activity and the activity start date have been Actualized (December 21 or December 12). I do notice that Early Start for this activity is Feb. 18.
I tried modifying the Duration: "remaining" and "at complete". I kept "remaining" at 0d; which keeps the date to Feb. 18; however, the "at complete" also gave me an same error message as above.
Questions:
1.) How do they calculate Remain Finish Date/Remain Start Date?
2.) From my observation, my assumption is that early start is causing the calculation of Remain Start Date to stay at Feb. 18. If my assumption is correct, what do I need to push it back to mid-January?
3.) What should I do?

The early start of Feb 18th means either a constraint or another acitivity is pushing it out the start to Feb 18th (or you data date is set there).
Check to see if there are any constraints on the activity.
Even though you say the predecessors are actualized, running with retainined logic will cause any acitivities to push out if ANY predesessors are not statused. You will need to look at the predecessors of the predecessors (in some cases all the way back to the first activity).
You can fix this by breaking the links to the non-finished predecessors or by changing the retained logic setting to progress override in the schedule options menu. This is usually not recommended and can cause unrealistic schedules.
Try and find an activity that ends on Feb 17th. More than likely this activity will be tied to the one you want to change.

Too many rows return on query?

I am trying to write a query to pull data from two different tables. There are 444 records in p table and 650 records in the T table yet when i run my query I am getting over 10,000+ records??? When I look at the results it seems that it is applying multiple dates per person when there is only 1 end date? and showing multiple languageid's when only 1 language is spoken?
SELECT DISTINCT P.LASTNAME, P.FIRSTNAME, T.LANGUAGEID, T.TEST_TYPE, T.END_DATE, T.SCORE1, T.SCORE2
FROM PS_TEST_SCORES T, PS_PERSONNEL P
WHERE T.SCORE1 >='2'
AND T.SCORE2 >='2'
AND T.END_DATE between to_date( '01-jan-2009 00:00:00', 'dd-mon-yyyy hh24:mi:ss' )
and to_date( '28-jan-2011 00:00:00', 'dd-mon-yyyy hh24:mi:ss' )
ORDER BY P.LASTNAME;
example result would be
jones john german test_type 24-dec-09
jones john german 22-jan-09
jones john german 01-feb-10
jones john spanish 05-aug-10

user11384952 wrote:
sorry .. I missed the join.. pardon that I am a newbie
I changed it to ....
SELECT DISTINCT P.SSN,P.LASTNAME, P.FIRSTNAME, T.LANGUAGEID, T.TEST_TYPE, T.END_DATE, T.SCORE1, T.SCORE2
FROM PS_TEST_SCORES T, PS_PERSONNEL P
WHERE SELECT DISTINCT P.LASTNAME, P.FIRSTNAME, T.LANGUAGEID, T.TEST_TYPE, T.END_DATE, T.SCORE1, T.SCORE2
FROM PS_TEST_SCORES T, PS_PERSONNEL P
WHERE PS_TEST_SCORE.SSN=PS_PERSONNEL.SSN
AND T.SCORE1 >='2'
AND T.SCORE2 >='2'
AND T.END_DATE between to_date( '01-jan-2009 00:00:00', 'dd-mon-yyyy hh24:mi:ss' )
and to_date( '28-jan-2011 00:00:00', 'dd-mon-yyyy hh24:mi:ss' )
ORDER BY P.LASTNAME;That can't be right: it has 2 SELECT clauses, 2 FROM clauses and 2 WHERE clauses.
Perhaps you meant
SELECT DISTINCT
          P.LASTNAME
,        P.FIRSTNAME
,        T.LANGUAGEID
,        T.TEST_TYPE
,        T.END_DATE
,        T.SCORE1
,        T.SCORE2
FROM        PS_TEST_SCORES     T
,        PS_PERSONNEL           P
WHERE        PS_TEST_SCORE.SSN     = PS_PERSONNEL.SSN
AND        T.SCORE1           >= '2'
AND       T.SCORE2          >= '2'
AND        T.END_DATE           between to_date ( '01-jan-2009 00:00:00'
                                , 'dd-mon-yyyy hh24:mi:ss'
                    and      to_date ( '28-jan-2011 00:00:00'
                              , 'dd-mon-yyyy hh24:mi:ss'
ORDER BY P.LASTNAME;Now you do have a join condition:
WHERE        PS_TEST_SCORE.SSN     = PS_PERSONNEL.SSNso that looks much better. In all the other conditions, you referred to the tables by their aliases, t and p, and not by their real names. You need to do that in this new condition, too:
WHERE        T.SSN     = P.SSN
now I get "PS_PERSONNEL.SSN invalid identifier"?
I ran a query to see what the constraint types are.. PK, FK?? on the tables and there is no PK or FK they all say "C" would that affect the join?
select *
from all_constraints
WHERE owner = 'OWNER' and TABLE_NAME LIKE 'PS\_%' ESCAPE '\'
order by table_name, constraint_type;constraint_type='C' means a CHECK constraint, which has nothing to do with joins.
constraint_type='R' indicates a referential integrity constraint, but that, at best, only hints at what a correct join condition might be.
No kidding: if you want help, the best thing is to post a little sample data (CREATE TABLE and INSERT statements) and the results you want from that data.

Pulling my hairs for a valid pdf signature

Using Acrobat Pro 9 with a new server certificate from a different CA I've been trying to put a valid signature in a pdf file. For some reason acrobat is giving me the "Signature is invalid" message with a red cross. When I open the Certificate-details dialog I see a "!" at the bottom with the message "The selected certificate path has errors: Invalid policy constraint". I'm not really sure what this means? which constraints are invalid? Then I read acrobat can make a log file during the validation process so I wondered if this could help, I got something like this (I edited some parts to protect my client):
20110913195706Z:
20110913195706Z: Validating cert graph with 1 chains
20110913195706Z: Validating chain: CertChain_[edit] Length = 5
   20110913195706Z: ----ChainBuilder----
      20110913195706Z: Processing Certificate: DN: cn=[edit] CA - G2, o=[edit], c=NL Serial: [edit]
      20110913195706Z: verification time = 20110913131236+0200
      20110913195706Z: Processing Certificate: DN: cn=[edit] - G2, o=[edit], c=NL Serial: [edit]
      20110913195706Z: verification time = 20110913131236+0200
      20110913195706Z: Processing Certificate: DN: cn=[edit] - G2, o=[edit], c=NL Serial: [edit]
      20110913195706Z: verification time = 20110913131236+0200
      20110913195706Z: Processing Certificate: DN: cn=[edit] - G2, o=[edit], c=NL Serial: [edit]
      20110913195706Z: verification time = 20110913131236+0200
      20110913195706Z: Processing Certificate: DN: cn=[edit], ou=[edit], o=[edit], l=[edit], st=[edit], c=NL Serial: [edit]
      20110913195706Z: verification time = 20110913131236+0200
      20110913195706Z: Chain builder added trouble flags 0x200
   20110913195706Z: Finished Chain Validation. TroubleFlags: 200
20110913195706Z:
I'm particularly interested if anyone knows what this line "Chain builder added trouble flags 0x200" means???
Any help is greatly appriciated!

Hi lullolullo,
You've come the right place. Signature validation starts with trust. If you don't trust the signer, or one of the certificates in the signing chain then nothing happens. A signature chain looks something like this:
Big Time CA Root Cert
    Intermediate Certificate Authority
        End-Entity (the signer, or in this case, you)
You have to assign trust to at least one of the certificates in the signature chain. You can either add trust via the Manage Trusted Identities dialog, or, via a preference where you can inherit trust from the Windows Certificate Store (Windows only, no Mac). To see the chain in the signature you are looking at do the following:
Right Mouse Click on the signature
Select Show Signature Properties from the pop-up menu
Click the Show Certificate button on the Signature Properties dialog
The chain is displayed in the tree view on the on the left side of the dialog
If you select the Trust tab and then select the different certificates in the chain view you will be able to see which one is the trust anchor.
Enough about trust, on to Policy Restrictions. When a Certificate Authority (CA) issues certificates they will often add the Certificate Policy extension. You can find this by selecting the Details tab and scrolling the list box for Certificate Policies. The policy is a long dotted number that acts as a marker for a specific set of rules. The rules themselves tend to be published online in a "Certificate Practice Statement" document, but that's getting a little beyond the scope of your problem. The rule might mean something like all certificates issues under this policy constraint are issued to employees of Company XYZ and have to be on a hardware token. That's an example of something you might see, but I'm not saying it the exact scenario you are facing.
The Root CA usually doesn't have a Certificate Policy extension, but all of the certs under it do meaning that this particular chain obeys a specific set of rules.
On to enforcing the rules. Let's say you have Big Time CA that issues certificates for IBM, Microsoft, Apple, and Adobe. Each one of those chains would contain a different Certificate Policy. Now let's say that I've trusted Big Time CA, which means every signature that created that chains up to Big Time CA would be trusted and valid. Now lets say I only want to trust the signatures that come from my fellow Adobe employees. What I would do is add a Policy Restriction to the trust setting, thus making trust more granular.
Next up, where to find the Policy Restriction. Select the Policies tab on the Certificate Viewer. When you are viewing the same certificate that is designated as the trust anchor do you see something in the Policy Restrictions group box? By something I mean data in the Certificate Policies edit field that will appear to be grayed out. If so then the signers certificate, and all of the other certificates in the chain have to have the Certificate Policy Extension with that number in it.
If the restriction is there, you can remove it by going to the Manage Trusted Identities dialog, which you get to from the Advanced menu. From there you need to select Certificates from the Display drop-down list. Find the certificate that corresponds to the trust anchor, selected from the list box, and then click the Edit Trust button. Finally, select the Policy Restrictions tab on the Edit Certificate Trust dialog. However, I'm not advising you to break any company policy if they want the restriction in place.
Steve

Unique Index vs. Unique Constraint

Hi All,
I'm studying for the Oracle SQL Expert Certification. At one point in the book, while talking about indices, the author says that a unique index is not the same a unique constraint. However, he doesn't explain why they're two different things.
Could anyone clarify the difference between the two, please?
Thanks a lot,
Valerio

A constraint has different meaning to an index. It gives the optimiser more information and allows you to have foreign keys on the column, whereas a unique index doesn't.
eg:
SQL> create table t1 (col1 number, col2 varchar2(20), constraint t1_uq unique (col1));
Table created.
SQL> create table t2 (col1 number, col2 varchar2(20));
Table created.
SQL> create unique index t2_idx on t2 (col1);
Index created.
SQL> create table t3 (col1 number, col2 number, col3 varchar2(20), constraint t3_fk
2                   foreign key (col2) references t1 (col1));
Table created.
SQL> create table t4 (col1 number, col2 number, col3 varchar2(20), constraint t4_fk
2                   foreign key (col2) references t2 (col1));
                 foreign key (col2) references t2 (col1))
ERROR at line 2:
ORA-02270: no matching unique or primary key for this column-listIt's like saying "What's the difference between a car seat and an armchair? They both allow you to sit down!"

Time Constraint Error when calling a Function module from Webdynpro ABAP

Any help will be greatly appreciated - Thanks RM
Time Constraint Error
Information on where terminated
    Termination occurred in the ABAP program "SAPUP50R" - in
     "CHECK_TIME_CONSTRAINT_S1".
    The main program was "MP000000 ".
    In the source code you have the termination point in line 1069
    of the (Include) program "UP50RU01".
Error occurred during batch input processing
Source Code Extract
      l_is_inconsistent = 'X'.
    ENDIF.
Check if there are inverted time periods.
    IF l_prelp_line-begda > l_prelp_line-endda.
      l_is_inconsistent = 'X'.
    ENDIF.
Check if there are overlaps or gaps.
    IF NOT l_prelp_before IS INITIAL.
      l_date_difference = l_prelp_line-begda - l_prelp_before-endda.
      IF l_date_difference <> 1.
        l_is_inconsistent = 'X'.
      ENDIF.
    ENDIF.
    l_prelp_before = l_prelp_line.
ENDLOOP.
IF l_prelp_before-endda <> '99991231'.
    l_is_inconsistent = 'X'.
ENDIF.
IF l_is_inconsistent = 'X'.
    IF p_access_type = 'R'.
490 Datenbankschiefstand Personalnummer & Infotyp &
      MESSAGE x490 WITH l_prelp_before-pernr l_prelp_before-infty.
    ELSE.
491 Unzulässige Daten Personalnummer & Infotyp &
Line 1069 Error occcurs >>>> MESSAGE x491 WITH l_prelp_before-pernr l_prelp_before-infty.
    ENDIF.
ENDIF.
ENDFORM.                    " CHECK_TIME_CONSTRAINT_S1     "XYVN0352581
*&      Form clear_no_adapter_needed              new     "XREN844998
      text
FORM clear_no_adapter_needed .
CLEAR no_adapter_needed.
ENDFORM.                    " clear_no_adapter_needed
*&      Form set_no_adapter_needed              new     "XREN844998
      text
FORM set_no_adapter_needed .
no_adapter_needed = 'X'.
ENDFORM.                    " clear_no_adapter_needed

Hi,
Well, are you trying to do a batch input on infotype 0000? If yes you need to check that the proposed values respects the time constraint, meaning no gap, no overlaps and no inversions. Also fields SUBTY, OBJPS, SPRPS and SEQNR must remain initial when processing IT0000...
Kr,
Manu.

How do you allow Unix based ONC RPC within the security constraints of SGD

On our new boxes running SGD 4.2.91and up we notice that our applications that uses rpc to communicate no longer work. One of the programs, the arbitrator, (i.e. runs in its on process space, not a linked in library). Therefore, two user will share the same arbitrator (or conversely, only one arbitrator runs per machine). The arbitrator runs without a display (i.e. has no stdout, etc, similar to a daemon). The arbitration process also uses the UNIX kernel resource of shared memory. Here is what I have observed with my testing. The arbitrator routine is successfully registered in the port map ( svc_register). This means it does run. But later when svc_run is called, the process is not found ( actually the select fails), and ps �ef | grep arbitrator indicates that the arbitrator is not running

Does SGD put any restrictions/constraints on ONC RPC, ie does it attempt to block or authenicate?
What object list_attributes does the application that luanches arbitrator need?
Does abribrator need to be in the list of allow applications for the current user? Can it be put in this list and not have an icon on the desktop ( since the user does not manually launch it, and usually is not even aware of it)?
Or, more generally, how does the enumerated allowed list of executables handle a process that exec/forks a new process? ie does SGD have to know the forked process name, etc?

Shortest path with more than one traveler and time constraints

Please have a look at this problem...Thank you..
(the problem is ok with one traveler. but when two or more come into the picture they really mess things up)
Here it is
I have a number of destinations that devides evenly up between a
number of travelers. (5 travelers with 20 destinations = 4
destinations each)
All destination can be visited by all travelers but it can ony be visited once
Each destination has to be visited and
each traveler has to visit the same amount of destinations.
The total amount of traveling has to be minimized.
Grid references have been given to work out the distance between each
destination. (the distances have not been worked out prior to the
start of the problem)
The starting point of each traveler is not at any of the destinations
and is different to each other. This point is also known and can be
used to calculate the distance to any destination.
there is an extra part of the problem (which I think I can sort out but if its of interest here it is any way): Each destination can only be
visited at a certain time of the day (ie between 7- 9 and 9-12 and
12-3 and 3-6)
A typical problem would have about 300 destinations and about 50
travelers every day. ie about 6 destination a day per traveler.
Could any one please give me an idea of how you would go about working the
routes out for each traveler that minimizes travelling distance as there is no algorithm that does this kind of routing.
I would really like some help with this one please. I have many ideas of how to do it but i really feel like it is not optimised...
I have to complete this in one week and have no AI experiance ( I would like to do this without AI or anything to do with ant colonies and or swarm optimization)
Thank you.

The reason that the time is in fact a simple constraint is because this is a homework problem and the kids only have a week to work on it. If it were a real world problem you you not conveniently have the number of travelers divide evenly into the number of cities.
If it were not some homework problem you would not have a constraint that reads "Oh by the way, for extra credit, you can only visit some cities at certain times during the day." It would either be a real constraint or not.
The other indication that it is a homework problem is that the student was given a week to do it. I will perhaps be going out on a limb here, but NO reasonable business gives some bozo one week to complete an assignment for which the bozo is so clueless that he has to hit the net and ask random people if they can tell him how to do it.
Had there been any need to model travel time, then velocity of travelers would have been mentioned at some point. If the traveler were actually doing anything in a city, time to load or unload the truck would have been given. And lastly, what real world problem would add a constraint that no two travelers could go to the same city. What if it is shorter to get from A to C by going through B which has already been visited. This constraint was the tip that the solution was a partition of a set of cities.
My gross simplification is merely that this is a homework problem and therfore if I haven't been told otherwise I am free to assume that a traveler moving at infinite velocity is perfectly OK. This means that my traveler waits at the door to a city until it opens, picks off that city and all other in zero time, until it bangs up against a city that opens at a later time, where it must again wait till opening time. The only thing that prevents him from completing his circuit is if an early city comes after a late city. A simple sort is all you need.
Lastly, even if you want to toss in a more complicated velocity model, it does little more than mildly complicate the sort comparison calculation so instead of making the comparison
boolean ICanMakeIt = city.openingTime <= city[i+1].openingTime
it becomes
boolean ICanMakeIt = city.exitTime +
Traveler[j].vel*dist(i,i+1) <= city[i+1].closingTime
I think you are mistaken in declaring this to be a difficult modeling problem

Meaning Of a "CONSTRAINT"

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